Having Respect for your Opponents:
This isn't a "shake hands and say gg" article. As misleading as the title is, it's still relevant.
I supposed a more fitting name would be Have Respect for your Opponent's Plays. This is the scenario when you have a 0/4 defender and they have a 2/2 and swing. Or they swing with the board even though it means they lose. This also happens in League of Legends where someone purposefully goes out of position.
Your opponent isn't messing up. He knows what he's doing.
In Magic: the Gathering this might be less prevalent, simply because it's turn-based so:
1. It gives you time to think about your decisions.
2. All the information you need to know is visible. (Count untapped lands/resources, ask for number of cards in hand.)
Of course, this assumes proper play. In low levels of play you would think your opponent messed up and block normally but your opponent would get a trade off or worse, 2-for-1 you. In middle play you expect your opponent to be full of answers, and wouldn't take the bait unless you had a counter-answer. It is much safer to take two points of damage than to potentially lose a card on the field.
Of course at high levels of play it's almost expected to know deck archetypes and stuff, and because you know your opponent knows, it can make for some very interesting plays, namely bluffs. Being able to get a play go through because you did nothing is somewhat satisfying in an evil way.
Either way, have respect for your opponents--they didn't mess up, it's a trap.